Logic devices may operate according to logical inputs and voltage supplies provided to the logic devices. The logic devices may be subjected to noise and variations in power levels as a result of the electrical characteristics of the system in which the logic devices operate.
Logic devices may be tested as stand-alone devices or in groups that estimate the electrical characteristics of the system in which the logic devices operate. In general, conventional testing systems may provide test inputs and a voltage supply to the logic devices and examine the resulting outputs generated by the logic devices in response to the test inputs. For example, test inputs may include patterns of signal levels that generate a corresponding response from the logic devices. If the logic devices are functioning properly, the response corresponds to the test inputs. The logic devices may, thereby, be accepted or rejected based on the response of the logic devices when subjected to the test inputs and voltage supply.
Conventional testing systems may provide the test inputs and voltage supply described above during a particular phase of the test procedure. For example, the testing system may provide the test inputs and voltage supply during a first testing phase. When the first testing phase ends, the system may provide new test inputs and voltage supply corresponding to a second phase of testing. As the performance and complexity of logic devices increase, there is an increasing need for improved testing of logic devices.